Comparison of Even-Order Elliptic Equations

Let Ω be an unbounded open subset of Rⁿ , and let L be a uniformly strongly elliptic differential operator defined by (1) L u : = ∑ | α | , | β | = 0 m ( − 1 ) | α | D α [ A α β ( x ) D β u ] ( x ∈ Ω ⊆ R n ) , https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781003072140/faeac70b-e389-4ea4-8b5b-5a836c2a1f73/content/eq2174.tif"/>